[ntpwg] WG: Minutes from NTP WG Interim meeting Fri Oct 14, 2016

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https://www.ietf.org/proceedings/interim-2016-ntp-05/minutes/minutes-interim-2016-ntp-05-201610141000-02


NTP WG Interim Meeting - Boston
Friday October 14, 10:00 am - 5:00 pm

Chairs: Karen O Donoghue and Dieter Sibold

Agenda
======

1.  Overview/summary of updates from the core security documents 
(explanation of the documents):
    draft-ietf-ntp-network-time-security
    draft-ietf-ntp-using-nts-for-ntp
    draft-dfranke-nts
        (no discussion planned, but included here for completeness as part 
of
         the suite of security documents thus far)
    draft-ietf-ntp-cms-for-nts-message

    Dieter presented a preliminary merged documents of the two drafts 
draft-ietf-ntp-using-nts-for-ntp and draft-dfranke-nts (for more details 
refer to the session's materials section).

    Decisions:

    1)      What key exchange (KE) protocol to use?

    1.a)    Do we want to allow optional key exchange mechanisms? 
(Alternative KE protocols).
            Decision: NO.

    1.b)    KE for the client server mode (mode 3/mode 4):
            Decisions:
                - TLS out of band to establish keys. then transmission of 
timing information is done with custom protocol from daniel's draft over 
UDP/123.
                - smuggling DTLS KE over NTP extension fields is tabled 
for now.
    
    1.c)    KE and transport for symmetric peering mode (mode 1/mode 2):
            Decision:
                TLS (alternatively DTLS) on a port other than UDP/123 to 
establish keys, and then timing information is carried over the TLS record 
layer.

    1.d)    KE and transport for control mode (mode 6) 
            Decision:
                DTLS on a port other than UDP/123 to establish keys. then 
timing information is carried over the DTLS record layer.

    1.e)    Open question for mode 1,2,6: 
                * what port to run the handshake on? 123 or other port?
                * what port to run the timing exchange on? 123 or other 
port?

    2)      Privacy considerations
                - Need to write down the objective in the draft, which 
seems to be:
                    -   prevent linkability of client even if the client 
does not know that its IP
                        address has changed from IPa to IPb. We do not 
want a *passive* monitor to use info in the NTP/NTS packet to link  IPa 
and IPb.
                    -   Some justification in the draft for the use case 
for which the client does  not know that its IP address has changed.
    
                - Daniel to provide some performance numbers to give us an 
idea of the performance of his protocol as currently written in draft, and 
also with encryption of the NTP header added.

                - Decision: Fix legacy client linkability issues in the 
NTP header, because if we don't fix them, all the mechanisms used to 
prevent linkability in NTS have little point.  Roughly, the idea is to 
zero out all identifying fields in the client query that are not used by 
the server. Aanchal and Daniel to draft this.



2.  Way forward for the various NTS documents (see above)
    - Clarify how Daniel and Kristof can work on the merged documents
    - Daniel will provide an update to the merged document according the 
decision above mentioned


3.  draft-aanchal4-ntp-mac
    Aanchal presented an update of the draft-aanchal4-ntp-mac. The new 
version of the draft recommends the use of CMAC because of a "nonce reuse 
vulnaribility" of a GMAC (for more details refer to the session's 
materials section)

4.  BCP draft-ietf-ntp-bcp
    Denis gave an update of the BCP. It is supposed to be ready for WGLC 
...

5.  Way forward for drafts related to extension fields and refid

    - draft-stenn-ntp-ipv6-refid-hash
    - draft-stenn-ntp-leap-smear-refid
    - draft-stenn-ntp-not-you-refid
    These three drafs shall be combined and resubmitted as 
draft-ietf-ntp-refid-updates as possible (Sharon and Harlan)


    - draft-mayer-ntp-mac-extension-field
    This draft should go forward

    - draft-stenn-ntp-last-extension
    - draft-stenn-ntp-i-do
    The processing on this document has been postponed to later

Jabber archive: https://www.ietf.org/jabber/logs/ntp/2016-10-14.html

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